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Overview
Comment:Minor fixes for sample code in eqp.in.
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 897bd4f88e4bfc4f3e22fffbcfc12e40cb3c2d20
User & Date: dan 2010-11-15 17:35:39
Context
2010-11-15
18:43
Add additional requirements marks and reword a few sentences in eqp.html. check-in: 09966391b1 user: drh tags: trunk
17:35
Minor fixes for sample code in eqp.in. check-in: 897bd4f88e user: dan tags: trunk
14:32
Add the Airbus logo to the "famous.html" page. Update the changes for 3.7.4. check-in: c0a45dd7fa user: drh tags: trunk
Changes
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Changes to pages/eqp.in.

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    2|0|0|SCAN TABLE t2 (~1000000 rows)
    2|0|0|USE TEMP B-TREE FOR ORDER BY
    0|0|0|COMPOUND SUBQUERIES 1 AND 2 (EXCEPT)
</codeblock>)^

<h1>Sample Code</h1>
















<codeblock>
/*
** Argument pStmt is a prepared SQL statement. This function compiles
** an EXPLAIN QUERY PLAN command to report on the prepared statement,
** and prints the report to stdout using printf().
*/
int printExplainQueryPlan(sqlite3_stmt *pStmt){
  char *zSql;                     /* Input SQL */
  char *zExplain;                 /* SQL with EXPLAIN QUERY PLAN prepended */
  sqlite3_stmt *pExplain;         /* Compiled EXPLAIN QUERY PLAN command */
  int rc;                         /* Return code from sqlite3_prepare_v2() */

  zSql = sqlite3_sql(pStmt);
  if( zSql==0 ) return SQLITE_ERROR;

................................................................................
  sqlite3_free(zExplain);
  if( rc!=SQLITE_OK ) return rc;

  while( SQLITE_ROW==sqlite3_step(pExplain) ){
    int iSelectid = sqlite3_column_int(pExplain, 0);
    int iOrder = sqlite3_column_int(pExplain, 1);
    int iFrom = sqlite3_column_int(pExplain, 2);
    const char *zDetail = sqlite3_column_text(pExplain, 3);

    printf("%d %d %d %s\n", iSelectid, iOrder, iFrom, zDetail);
  }

  return sqlite3_finalize(pExplain);
}
</codeblock>







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    2|0|0|SCAN TABLE t2 (~1000000 rows)
    2|0|0|USE TEMP B-TREE FOR ORDER BY
    0|0|0|COMPOUND SUBQUERIES 1 AND 2 (EXCEPT)
</codeblock>)^

<h1>Sample Code</h1>

<p>Sometimes, within a large application, it may be inconvenient to modify
code to generate EXPLAIN QUERY PLAN commands for the SELECT queries being
investigated. From within an interactive debugging session, it may be almost
impossible. In these situations, a function similar to the following may
be useful. This particular function is passed an SQLite statement handle as an
argument and outputs the corresponding EXPLAIN QUERY PLAN report to standard
output. Application specific versions may output the report to an application
log or similar.

<!--
** WARNING: The following function, printExplainQueryPlan() is duplicated
** in file test1.c of the source distribution for testing purposes. If
** the code below needs to be modified, the copy in test1.c should also
** be modified and the Tcl tests run.
-->
<codeblock>
/*
** Argument pStmt is a prepared SQL statement. This function compiles
** an EXPLAIN QUERY PLAN command to report on the prepared statement,
** and prints the report to stdout using printf().
*/
int printExplainQueryPlan(sqlite3_stmt *pStmt){
  const char *zSql;               /* Input SQL */
  char *zExplain;                 /* SQL with EXPLAIN QUERY PLAN prepended */
  sqlite3_stmt *pExplain;         /* Compiled EXPLAIN QUERY PLAN command */
  int rc;                         /* Return code from sqlite3_prepare_v2() */

  zSql = sqlite3_sql(pStmt);
  if( zSql==0 ) return SQLITE_ERROR;

................................................................................
  sqlite3_free(zExplain);
  if( rc!=SQLITE_OK ) return rc;

  while( SQLITE_ROW==sqlite3_step(pExplain) ){
    int iSelectid = sqlite3_column_int(pExplain, 0);
    int iOrder = sqlite3_column_int(pExplain, 1);
    int iFrom = sqlite3_column_int(pExplain, 2);
    const char *zDetail = (const char *)sqlite3_column_text(pExplain, 3);

    printf("%d %d %d %s\n", iSelectid, iOrder, iFrom, zDetail);
  }

  return sqlite3_finalize(pExplain);
}
</codeblock>